grease pencil jagged lines
i think this will solve your problem. At the Draw menu go to :


Options -> Check Post-processing menu 
Subbdivision Steps (1 -> 3)
(Optional) Smooth (0.1 -> 2)


The quality of the stroke (number of points added which you can see in Edit mode) is inversly proportional to the drawing speed.
Sorry for my English, Hope it helps !